(literally) A gunshot wound to the head. / (colloquial, in similes) Something very undesirable or unwanted.

plural of memory hole

plural of placket hole

(now historical) A slit in a woman's outer skirt allowing access to pockets, items etc. kept inside.

(idiomatic) A bar or other local drinking establishment.

plural of Johnson hole

(military slang, now historical) A large shell crater during the First World War.

(astrophysics) A region in the corona of a star where magnetic field lines extend out into space, allowing solar wind to escape.

plural of coronal hole

A saw in the form of a hollow cylinder with teeth on the end or edge, used to produce holes on the workpiece and operated by rotation, often as an accessory to a power drill.